Pressure fluid extinguishing device for a circuit breaker

ABSTRACT

An extinction device for a pressurized gas cut-off appliance has holes, in its side walls, through which a lateral auxiliary flow of sulphur hexafluoride is made to pass.

United States Patent [191 l l i 3,708,639

Vigreux et al. 1 Jan. 2, 1973 [54} PRESSURE FLUID EXTINGUISI'IING [56] References Cited DEVICE FOR A CIRCUIT BREAKER UNITED STATES PATENTS [75] Inventors: Jacques Vigreux, Lyon; Bernard Tromet vineurbanne, both of 3,150,245 9/l964 Leeds et al. ZOO/148 G France Primary Examiner-Robert S. Macon [73] Asslgnee' neue'Alsthom v' France Attorney-Sughrue, Rothwell, Mion, Zinn & Macpeak [22] Filed: Jan. 14, 1971 211 Appl. No; 106,422 [57] ABSTRACT An extinction device for a pressurized gas cut-off appliance has'holes, in its side walls, through which a [30] Forelgn Application Prlomy Data lateral auxiliary flow of sulphur hexafluoride is made Jan. 6, 1970 France ..700l607 to pass.

52 us. Cl. ..200/14a R 10 Claims, 7 Drawing Figures {51] Int. Cl...... ..H01h 33/54 [58] Field ofSearch ..200/l48 A, 148 C, I506, 200/148 R PATENTEDJAN 2197s SHEET 3 0F 3 PRESSURE FLUID EXTINGUISI-IING DEVICE FOR A CIRCUIT BREAKER BACKGROUND OF THE INVENTION 1. Field of the Invention The invention concerns electrical circuit breakers wherein the arc is extinguished by means of a current of fluid under pressure.

2. Description of the Prior Art In these apparatuses, it is attempted to prevent the insulating walls of the extinguishing devices subjected to the action of the arc, such as nozzles, tuyeres and breaker chambers, for example, from becoming conductive under the direct action of the arc, the hot gases or the conductive deposits consequent on the interruption of the current.

It is known to provide the surface of the devices subjected to the direct action of the arc or the hot gases with grooves and steps arranged substantially perpendicularly to the direction of tensile stress which appears after breaking. These grooves or steps can be made from insulating materials, conductive materials or a combination of these two materials. This arrangement is not always satisfactory.

SUMMARY OF THE INVENTION The present invention has as its object to provide an arrangement which makes it possible to considerably reduce the action of the are on the'walls of the extinguishing devices, by moving the arc away from the walls.

It is characterized more particularly in that the extinguishing device comprises orifices arranged in its lateral walls through which an auxiliary transverse blowing action is carried out.

According to another feature of the invention, each orifice is in communication with a chamber arranged within the wall of the extinguishing device.

According to yet another feature of the invention, each chamber is connected to a common internal chamber.

According to yet another feature of the invention, this circuit breaker comprises a ring of magnetic material arranged in its mass coaxially with the direction of the arc.

The interposing of a sheath of gas between the walls and the arc has as its object to remove the arc from the smooth or stepped walls. The use of a magnetic device also makes it possible to center the arc in the extinguishing device. In this way, the arc tends to keep away from the walls, on the one hand during its existence, which reduces its direct action on the walls and the influence of the. hot gases and the depositing of metallic vapors. More especially, this occurs during the period preceding the passage of the current through zero, that is to say, immediately before the appearance of the tensile stress, which effects a sufficient cooling of the wall and the gases in contact with the latter thus making it possible to withstand the tensile stress without re-striking the arc.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 to 7 are sections taken along the axis of blowing nozzles corresponding to various constructional variants.

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to FIG. 1, grooves l are formed in the duct 2 of the nozzle 3 through which the blast fluid passes. These grooves l are in communication with preferably annular chambers such as 4. When the arc develops axially of the duct 2,-gases under pressure heated by the arc enter the grooves l (or otherwise through orifices of any kind communicating with the chambers 4 and taking the place of the grooves 1) into the chambers 4 where they become cooled. When the current tends towards zero and immediately prior to extinction of the arc, the gas is re-introduced into the duct 2, it tends to re-center the arc and to move it away from the wall, and the addition of cooled gas lowers the temperature of the wall and insures the dielectric regeneration of the volume contained in the duct 2. This arrangement, applicable to any breakers operating by the use of a pressure fluid flow, is particularly important for certain breakers operating by self-compression wherein the compressed gas blown onto' the arc is strongly heated and whose dielectric strength is consequently lowered by the elevated temperature.

Furthermore, in these devices, 'the extinction of the arc should be obtained economically by the blowing of a limited gas volume, and the addition of a relatively fresh gas at the instant of extinction has a favorable influence on the breaking action.

According to a variant of FIG. 2, the chambers 4 communicate with a chamber 5 which is preferably annular and communicates with all the chambers 4 by means of conduits 6. This arrangement not only makes it possible to release at the moment of extinction a greater quantity of cooled gases (which could be obtained by increasing the volume of the chambers 4), but the orifices 6 effect a supplementary expansion of the gas and increase the cooling effect, and permit of better adjustment of the delivery rate.

The delivery of blown gas along the wall of the nozzle can be increased by using the arrangement shown in FIG. 3 and connecting the chamber 5 to the chamber 7 situated upstream of the nozzle and from which the compressed gas comes. For example, according to FIG. 3, a piston 14 sliding in a cylinder 15 compresses the gas and the latter flows both through the duct 2 of the nozzle and into the orifices 8 of considerable cross-section which supply the chamber 5.

It is also possible, in a variant, to dispense with the chambers 4 of FIGS. 2 and 3 and to connect the chamber 5 directly to the grooves l.

In FIGS. 1, 2 and 3, the element of the nozzle and the auxiliary blowing arrangement are constituted by insulating materials. According to the constructional arrangement shown in FIG. 4, the discs 9 in contact with the arc are conductive and generally made of metal.

The number of discs 9 is greater, in proportion, as the arc voltage is increased, so as to prevent elementary arcs from short-circuiting the conductive discs.

The arrangements shown in FIGS. 1 to 4 make it possible to obtain the result that, after the extinction of the arc, an additional blowing action occurs which cools the wall and the gaseous medium in the nozzle and contributes to preventing re-striking after breaking.

Furthermore, the deterioration phenomena in the insulating materials and the difficulties which the latter have in withstanding the tension which re-appears after the interruption of the current are all the more reduced in proportion as the column of the arc is further positioned from the walls during the passage of the current. When the arc is developed in a duct such as 2, it is advantageous to maintain the arc axially of the duct. The auxiliary blowing of gas provided for by the arrangements shown in FIGS. 3 and 4, which occurs not only in the vicinity of extinction such as is the case with FIGS. 1 and 2, but also during the entire existence of the arc, promotes the maintaining of the arc axially of the duct and reduces damage to the materials constituting the duct.

To obtain better centering of the arc, it is possible in every case, and whether nozzle does or does not comprise an auxiliary blowing arrangement as shown in FIGS. 1 to 4, to provide the nozzle with a ring of magnetic material as shown in FIG. 5. This ring promotes the cooling of the walls, improving the centering of the arc mainly when the current is tending towards zero.

In FIGS. 1 to 5 there is shown by way of example a blowing nozzle comprising a cylindrical duct. As a variant, it is possible to use, as FIG. 6 shows, a blowing nozzle comprising a duct 16 defining a conical duct. In this arrangement, the mobile contact 11 to which the arc is attached after separation of the mobile contact 11 and fixed contact 17, is displaced axially of the duct and during opening is moved progressively away from the insulating wall. Under these conditions, to withstand the dielectric stress, to the creepage path. distance along an insulating element there is added consecutively an increasing distance in a gas, which improves stability under tension since the dielectric regeneration of the gas is more rapid than the dielectric regeneration of the insulating element at the creepage path.

As a variant, according to FIG. 7, there can be used a blowing nozzle comprising a conical passage portion 16 prolonged by a cylindrical passage portion 12 forming a deflector for the hot gases and protecting the insulating walls situated in the vicinity such as for example the insulating cylinder 13 which is coaxial with the nozzle and constitutes the envelope of the breaker chamber.

The blowing nozzles in FIGS. 6 and 7 can be provided'with the improvements described in FIGS. 1 to 5 which are intended to cool the walls and improve the centering of the arc. In a general way, the various arrangemen ts described may be combined or used separately without departing from the framework of the invention.

Breaking tests have shown that the improvement in the centering of the arc, the improvement of the dielectric strength during interruption, the cooling and protection of the insulating walls which result from the adoption of the arrangements described substantially improve the results of the breaking: increase in the amount of current which can be interrupted, reduction in arc time, interruption with increased voltage reestablishment speeds. To give one example, other things being equal and varying only the voltage reestablishment speed, the following results are observed: the same limit break current is obtained with voltage re-establishment speeds of 2, 2.5 and 5 kilovolts per microsecond respectively for a cylindrical nozzle having smooth walls, a divergent conical nozzle having smooth walls and a cylindrical nozzle whose walls are provided with the features of FIGS. 1 or 3.

What is claimed is:

1. In an extinguishing device for a circuit breaker having a source of fluid under pressure and means for passing said fluid axially through a nozzle for blowing out the arc, the improvement comprising:

auxiliary blowing means defined by a plurality of transverse grooves within the lateral walls of said nozzle in planes axially spaced from each other, and

at least one enlarged chamber provided within said lateral walls and communicating with said transverse grooves.

2. The extinguishing device according to claim 1, wherein: each transverse groove is in communication with an individual enlarged chamber.

3. The extinguishing device according to claim 2, wherein: each individual enlarged chamber is connected to a common internal chamber.

4. The extinguishing device according to claim 1, wherein: each transverse groove is in communication with a common enlarged chamber.

5. The extinguishing device according to claim 3, wherein: said common internal chamber is connected directly to the source of blowing fluid.

6. The extinguishing device according to claim 1, wherein: the grooves are formed by the gaps formed in an assembly of conductive discs.

7. The extinguishing device according to claim 1, wherein: a ring of magnetic material is arranged in the nozzle mass coaxially with the direction of the are.

8. The extinguishing device according to claim 1, wherein: the device is constituted by a cylindrical nozzle.

9. The extinguishing device according to claim I, wherein: said device is constituted by a nozzle the duct opening of which is in the form of a cone prolonged downstream by a cylinder.

10. The extinguishing device according to claim 1,

wherein: the blowing fluid is sulphur hexafluoride. 

2. The extinguishing device according to claim 1, wherein: each transverse groove is in communication with an individual enlarged chamber.
 3. The extinguishing device according to claim 2, wherein: each individual enlarged chamber is connected to a common internal chamber.
 4. The extinguishing device according to claim 1, wherein: each transverse groove is in communication with a common enlarged chamber.
 5. The extinguishing device according to claim 3, wherein: said common internal chamber is connected directly to the source of blowing fluid.
 6. The extinguishing device according to claim 1, wherein: the grooves are formed by the gaps formed in an assembly of conductive discs.
 7. The extinguishing device according to claim 1, wherein: a ring of magnetic material is arranged in the nozzle mass coaxially with the direction of the arc.
 8. The extinguishing device according to claim 1, wherein: the device is constituted by a cylindrical nozzle.
 9. The extinguishing device according to claim 1, wherein: said device is constituted by a nozzle the duct opening of which is in the form of a cone prolonged downstream by a cyLinder.
 10. The extinguishing device according to claim 1, wherein: the blowing fluid is sulphur hexafluoride. 